One of the great things about the Archer Airguns XMV Tune Kit is that it’s so easy to tell if your individual gun will benefit from it.
All that’s necessary is to drag a ruler across the rear of the barrel, just as shown in this photograph. Carefully feel what happens as the ruler passes over the breech seal area.
Note that the barrel has been removed from the gun for clarity in these two photographs.
1. If there’s no resistance at all to the ruler from the breech seal, this indicates that the breech seal is NOT projecting from the barrel and is thus providing no sealing effect at all. This is the “maximum benefit case” where the XMV Tune Kit will give a huge benefit to muzzle velocity - 80fps or more.
2. If the rules just catches, or drags slightly, on the breech seal, then there’s some loss of air when shooting and the muzzle velocity definitely will be increased by installing the kit. The increase will be about 50 - 60fps.
3. If you feel a definite bump with the ruler, you’re one of the lucky few whose gun already has good sealing. But even here, replacing the factory breech seal with the superior quality part supplied in the XMV Tune Kit will give an increase of around 40fps.
So, it’s really just a question of “How much muzzle velocity do I gain?” when installing the Archer Airguns XMV Tune Kit for Ruger Air Hawk and Blackhawk.
SAFETY NOTE: Although it’s easy to test breech seal projection with a ruler, I strongly recommend making this a two person task. One person should hold the barrel firmly with the buttstock braced against the body and no finger anywhere near the trigger - as shown in the photograph. Do not release your grasp of the barrel at any time when making this test!
Then a second person can use the ruler. Obviously the gun will have been cocked for the test, so carefully load a pellet and fire safely at a target after testing.